DISSERTATION RESEARCH: The Ecomorphology of Arboreal Squirrels and the Evolution of Gliding Locomotion

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Researchers examining evolutionary divergence in locomotion characteristically rely upon a model of initial behavioral modification followed by secondary morphological change. Yet, studies of gliding performance in frogs suggest that concomitant changes in morphology and behavior may be required, making the behavioral precedence model untenable. Arboreal squirrels provide a perfect system to test the model since a transition from leaping to gliding likely occurred in this group. The objective of the proposed study is to determine whether the sequence of evolutionary changes from leaping to gliding is consistent with the behavioral precedence model. The study examines variation in three arboreal squirrels (flying squirrel, tree squirrel, chipmunk) and a close arboreal relative (dormouse) at the following levels: 1) Morphology; 2) Biomechanics; 3) Locomotor behavior; and 4) Ecology. The synthesis phase employs multivariate statistics to summarize variation in these levels and to identify significant trait differences among species. Traits are subsequently mapped onto the phylogeny to test behavioral precedence. In addition to testing the model, the study provides the first comparative examination of mammalian arboreal leaping outside of primates, and the only detailed description of mammalian gliding. Biomechanical descriptions of leaping and gliding locomotion may have important implications for those intending to use animals as model systems in engineering design.